Patent GB-681759-A (GB)
Title: Change speed gearing
IPC: F16H37/00
Filed: 1950-08-04
Abstract: 681,759. Change-speed gear. FULLER MANUFACTURING CO. Aug. 4, 1950 [Dec. 16, 1949], No. 19542/50. Class 80 (ii). An auxiliary gear 11 having two or more ratios which multiply a predetermined number of the ratios of a series main change-speed gear 10, e.g. on a vehicle, to provide overall two or more series of ratios, of which the lowest or highest in one series is higher or lower than the highest or lowest in another, whereby the series can be used consecutively, is controlled by a pre selector 113, Fig. 9, its shift being subsequently executed by the normal subsequent movement of the main change-speed lever, which latter moves always only in the normal shift-pattern associated with its own change-speed gear. Thus, after passing through all the ratios of the main gear, upwards or downwards, actuation of the preselector followed by return of the main shift-lever to the starting position, provides the first up, or down step of a new series, further steps of which are introduced by movement of the main shift-lever alone in the same shiftpattern as before. The main change-speed gear 10, shown, provides between its input and output shafts 15, 14, three reduced, direct, one overspeed and one reverse ratios, by dog clutches and a sliding reverse idler on an additional countershaft (Fig. 3, not shown), all controlled by a single shiftlever 22, operating through shift-rails 114-117, Fig. 9, interlocked by the usual guided balls 123 and drift-pins 121a. The auxiliary gear 11 provides between its input and a final output shafts 14, 54, direct and reduced drives controlled by a dog selector-clutch 81 with frictional synchronisers 79 such as to produce synchronism in a period (0.5 sec.) less than that normally taken in making a shift in the main gear. The reduction ratio (3.33 to 1) provided by the auxiliary gear is approximately one main gear-step greater than the engine speed range (2.58 to 1) between first and fourth speeds of the main gear. The selector clutch 81 is operated by a double-acting liquid or air pressure or vacuum cylinder 101 under control of a preselector-valve 102, connected by cable to a manual preselector 113 arranged near the main shift-lever. Pressure fluid or vacuum is supplied to the preselector valve 102 from a storage tank 108 through an executive valve 105, which is opened only when the main change-speed gear is in or near neutral, this operation being effected by the interlock drift-pin 121 of the adjacent main shift-rail 114, acting through a ball 122 and spring-loaded plunger 107. In this assembly, after starting with the auxiliary gear 11 in reduced drive and passing in the usual way through the first four ratios (not including overdrive) of the main gear 10, the preselector 113 is operated and the main shift lever moved back to its starting position; during which the auxiliary gear 11 is automatically upshifted to direct-drive and the main gear back to low, giving an overall upstep to the first of the new series, further steps, including overdrive, of which are obtained by movement, in its normal shift-pattern, of the main shaft lever only. Downshifts are similar, the preselector of the auxiliary gear being only operated at that step which changes over the series, as before. Numerical ratios are specified.